Vent pipe maximum horizontal run?

[dooman]

Hi all,

I have a quick question. I'm trying to vent the smell from an underground grease tank further away. If I use a 3" pipe and run it horizontally a distance of 20' will it work? Is there a maximum distance you can run a vent pipe horizontal before you have to go vertical? Thanks in advance.

Mike

[LazyPup]

BY code yo would not be permitted to do so. While 1/8 inch per foot is the required pitch for a drain vents come under a different regulation.

The code prohibits any horizontal dry vents.

When a vent must be offset the minimum pitch is 45 degs from vertical.